Electrical systems with packaged electrical and electronic components are known and are in use. For example, Motor Control Centers (MCC's) are used for power and data distribution in large and industrial operations. In MCC's, a variety of components, such as switchgear, semiconductor power electronic circuits, programmable logic controllers, motor controllers, and so forth, are housed in large electrical enclosures that may be subdivided into sections or columns, which may be further subdivided into compartments. The MCC includes associated bus bars, interconnections and supporting structures for distribution of electrical power to the various compartments.
Typically, the MCC is connected to a main power line that may feed three-phase AC power to horizontal bus bars of the MCC. The horizontal bus bars, in turn, may feed the three-phase power to vertical bus bars disposed in each of the sections or columns of the MCC. The vertical bus bars, in turn, may feed the three-phase power to various units (which typically include electrical components) that are installed in compartments of a section. The units, in turn, may provide power terminals (conductors), such as copper bus bars, for feeding the three-phase power to a system environment, such as motors, as may be required for various applications.
However, in order to meet minimum electrical short-circuit protections, such as in accordance with International Electrotechnical Commission (IEC) and/or Underwriters Laboratories (UL) standards, power conductors, including the power terminals provided for making electrical connections to system environments, typically must be sufficiently insulated and mounted with adequate distance from other conductive parts (including neighboring power conductors). Moreover, in order to meet increased electrical isolation and protection standards, such as in accordance with IEC 61439-2 Forms 3, 3a, 4 or 4b, power conductors typically must also be provided through electrical isolation barriers or boundaries, such as electrically conductive walls or plates.
Consequently, complex arrangements in which bent power terminals, insulating layers, base plates and fasteners are often required to provide power terminals while meeting such protection standards. For example, in one arrangement, a unit such as a circuit breaker may require a first set of bus bars interior to the unit, a second set of bus bars external to the unit, insulating layers between the internal and external bus bars along a conductive wall or plate (isolation barrier), adequate supports, and fasteners, such as bolts, screws, washers and/or nuts, for joining the first and second sets of bus bars. However, such arrangements can be costly, require long assembly times and be cumbersome to implement with a possibility of error.